Dispensers for insecticides are well known in the art and range from the active type to the passive type.
The active types of dispensers comprise aerosol cans containing an insecticide and propellant, or a liquid insecticide in a container with a manually operated or electrically operated pump, for driving the insecticide out in a mist or spray form.
The passive type of dispenser uses a container which is well ventilated and contains the insecticide in a solid or granular form which slowly volatilizes when exposed to the air.
There are several disadvantages in the known types of active dispensers. First, they dispense insecticide at a high rate, creating a heavy concentration of airborne insecticide in the vicinity of the user, which will inevitably be inhaled. Second, some of these dispensers require the handling of poisonous liquids by the user, which could be dangerous. Third, the aerosol can dispensers are not refillable, so they must be thrown away after they are exhausted.
There are also disadvantages to the passive type of dispensers. Their rate of volatilization is very slow and they are not effective for use in large areas because of this. Also, some of these dispensers are integral with the solid insecticide and are not reusable. Those that are reusable require disassembly for refilling while the solid or granular insecticide itself must be carefully packaged to prevent premature volatilization.
More specifically, it is known to provide a dispenser in which a volatizable material such as insecticide, may be driven by heating from a substrate in which the insecticide is adsorbed or absorbed, e.g. in the cellulosic material of the substrate. The same principle can be used for dispensing other materials from other solid substrates, the volatizable materials including air-cleaning agents, bactericides, disinfectants, cleaning agents and the like.